Israeli startup Kaltura announced the close of a financing round worth approximately $25 million on November 19.

Named the first of six fastest-growing tech companies by Forbes last week, Kaltura was founded in 2006 as the world’s first and only open-source online video platform for media management and custom app development. It has more than 150,000 clients including web publishers, media companies, enterprises, educational institutions and service providers.

The multibillion-dollar global e-commerce discounter Groupon uses Kaltura’s platform for internal communications. Other high-profile customers include Ivy League universities, HBO, Warner Brothers, Best Buy, SAP and Bank of America. Its newest client, announced November 13, is AOL On Network, which brings AOL’s entire video offering under one umbrella, and reaches more than 75 million unique visitors per month.

The newest Kaltura financing round was led by Tokyo-based Mitsui and Orix Ventures. They join existing backers 406 Ventures, Intel Capital, Nexus Ventures Partners and Avalon Ventures. The infusion is said to be earmarked for business development and hiring additional engineers and software developers to augment Kaltura’s Ramat Gan R&D staff of 100.

In addition to its Israeli headquarters, Kaltura has offices in New York, California and London.